Stackable air swirlers

ABSTRACT

A swirler includes an inner body defining a swirl axis. A plurality of swirl vanes extend outward from the inner body. The swirl vanes define respective swirl slots therebetween for imparting swirl on a fluid passing through the swirl slots. A method of making swirlers includes additively manufacturing a stack of swirlers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 16/248,137filed Jan. 15, 2019, now issued as U.S. Pat. No. 10,557,630 which isincorporated by reference herein in its entirety.

BACKGROUND 1. Technological Field

The present disclosure relates to nozzles and injectors, and moreparticularly to swirlers for nozzle and injectors such as used in fuelinjection for gas turbine engines.

2. Description of Related Art

Air swirlers, such as for use as inner air swirlers in fuel injectorsand nozzles, are traditionally difficult to make. Advanced enginedesigns have high requirements for performance including low emissions.This often translates into complex swirler designs. Using conventionalmachining the geometry, e.g., aerodynamic vane geometry, is intricateand therefore costly and time consuming. If turning slots are used,milling out the slots is time consuming and costly. Additivemanufacturing can accommodate a variety of geometries, but is also slowand expensive due to the fact that traditional additive manufacturingmachines do not have a large enough build plate to economically producea large number of swirlers.

The conventional techniques have been considered satisfactory for theirintended purpose. However, there is an ever present need for improvedswirlers and processes of making swirlers. This disclosure may addressat least one of these needs.

SUMMARY

A swirler includes an inner body defining a swirl axis. A plurality ofswirl vanes extend outward from the inner body. The swirl vanes definerespective swirl slots therebetween for imparting swirl on a fluidpassing through the swirl slots.

The inner body can follow a first cone angle that diverges in adownstream direction along the swirl axis. The swirl vanes can define afrustoconical volume that follows a second cone angle that converges inthe downstream direction. The swirl slots and swirl vanes can beoriented tangential to the swirl axis. An outer ring can be connected tothe swirl vanes and can provide an outward boundary to the swirl slots.The inner body can have a constant wall thickness. The inner body candefine a plurality of cooling holes therethrough inboard of the swirlslots.

A method of making swirlers includes additively manufacturing a verticalstack of swirlers as described above. Additively manufacturing thevertical stack can include building an external ring and an inner pointinside the external ring and additively manufacturing the vertical stackin a vertical build direction from the external ring and inner point.The inner body of a lower most swirler in the vertical stack canoriginate from the inner point. The method can include additivelymanufacturing a central support rod aligned with the swirl axis of theswirlers. The central support rod can support between adjacent swirlersin the stack so that the inner bodies of swirlers in the stack can bebuilt up, each starting from the central support rod and divergingtherefrom in the vertical build direction. The central support rod caninclude frangible features adjacent each swirler connected thereto andfurther comprising breaking the frangible features to separate theswirlers in the stack from one another. Breaking the frangible featurescan include twisting the swirlers relative to one another. The methodcan include separating the swirlers from one another by machining awaythe central support rod. An external tube outboard of the swirl vanescan be built up from the external ring to support the build fromoutside. The method can include machining the external tube away toseparate the swirlers from one another.

These and other features of the systems and methods of the subjectdisclosure will become more readily apparent to those skilled in the artfrom the following detailed description of the preferred embodimentstaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosureappertains will readily understand how to make and use the devices andmethods of the subject disclosure without undue experimentation,preferred embodiments thereof will be described in detail herein belowwith reference to certain figures, wherein:

FIG. 1 is a cross-sectional side elevation view of an exemplaryembodiment of a swirler constructed in accordance with the presentdisclosure, showing the swirler as an inner air swirler in a nozzle withan outer air cap and a fuel circuit between the inner swirler and outerair cap;

FIG. 2 is a cross-sectional side-elevation view of a stack of swirlerslike the swirler of FIG. 1, showing the stack after additivemanufacturing but before separation of the individual swirlers from thestack;

FIG. 3 is a partially cut away perspective view of an additivemanufacture build of swirlers like the swirler of FIG. 1, showing abuild plate with a plurality of stacks like that of FIG. 2 buildthereon;

FIG. 4 is a cross-sectional side elevation view of a portion of thestack of FIG. 2, showing the frangible features of the central supportrod; and

FIG. 5 is a cross-sectional side elevation view of the swirler of FIG.1, with a central bore therethrough.

DETAILED DESCRIPTION

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectdisclosure. For purposes of explanation and illustration, and notlimitation, a partial view of an exemplary embodiment of a swirler inaccordance with the disclosure is shown in FIG. 1 and is designatedgenerally by reference character 100. Other embodiments of swirlers inaccordance with the disclosure, or aspects thereof, are provided inFIGS. 2-5, as will be described. The systems and methods describedherein can be used to facilitate manufacture of swirlers, such as foruse as inner air swirlers in fuel injectors and nozzles.

The swirler 100 is seated as an inner air swirler in the inner airpassage 12 of a nozzle 10 that defines a fuel passage 14 outboard of theinner air passage 12 and an outer air passage 16 with an outer air cap18 outboard of the fuel passage 14. Fuel issued from the fuel passage 14is sheared between swirling air from the outer air swirler 18 and fromthe inner air swirler 100 to atomize the fuel spray indicated in FIG. 1by stippling for combustion, e.g., in a combustor of a gas turbineengine. Gaseous fuel can be used in addition to or in lieu of liquidfuel. The swirler 100 includes an inner body 102 defining a swirl axisA. A plurality of swirl vanes 104 extend outward from the inner body102, i.e. away from the swirl axis A. The swirl vanes 104 definerespective swirl slots 106 therebetween for imparting swirl on a fluid,e.g., air, passing through the swirl slots 106 from upstream of theswirler 100, i.e. the left side of the swirler 100 in FIG. 1, todownstream of the swirler 100, i.e. on the right side of the swirler 100in FIG. 1.

The inner body 102 is a conical body that follows a first cone angle 0which diverges in a downstream direction along the swirl axis A, i.e.the conical body 102 gets further from the swirl axis A the further tothe right it is along the swirl axis A in FIG. 1. The swirl vanes 104define a frustoconical volume, e.g. indicated by the dotted area in FIG.1, that follows a second cone angle a that converges in the downstreamdirection, i.e. the swirl vanes 104 get closer to the swirl axis A thefurther to the right they are in FIG. 1. Those skilled in the art willreadily appreciate that while the inner body and swirl vanes followconical geometries, it is not necessary for them to be strictly conical,e.g., they can follow any suitable curve. The swirl slots 106 and swirlvanes 104 are oriented tangential to the swirl axis A, in other words,the swirl slots 106 and swirl vanes 104 are not aligned along radii ofaxis A, but are offset from the radii of axis A as in a radial typeswirler. An outer ring 108 is connected to the swirl vanes 104 andprovides an outward boundary to the swirl slots 106. The inner body 102has a constant wall thickness T, and a plurality of cooling holes 110therethrough inboard of the swirl slots 106.

With reference now to FIG. 2, a method of making swirlers such asswirler 100 described above includes additively manufacturing avertical, nested stack 112 of swirlers 100. Additively manufacturing thevertical stack includes building an external ring 114 and an inner point116 inside the external ring 114 and additively manufacturing thevertical stack in a vertical build direction D from the external ring114 and inner point 116. The external ring 114 and inner point 116 canbe formed on a build plate 118, e.g. of a selective laser sinteringmachine. The inner body 102 of a lower most swirler in the verticalstack 112 originates from the inner point 116. The angle of the innerbody 102 is conducive to being built up from this central point 116 inadditive manufacturing machines. The method includes additivelymanufacturing a central support rod 120 aligned with the swirl axis A ofthe swirlers 100. The central support rod 120 supports between adjacentswirlers 100 in the stack 112 so that the inner bodies 102 of swirlers100 in the stack 112 can each be built up from a central point, with allthe swirlers but the lower most each starting from the central supportrod 120 and diverging therefrom in the vertical build direction D.

As shown in FIG. 4, the central support rod 120 includes frangiblefeatures 122, 124 adjacent each swirler 100 connected thereto. Eachfrangible feature 122 is just below the respective inner body 102 and isa frustoconical indentation in the cylindrical body of the centralsupport rod 120. Each frangible feature 124 is a similar frustoconicalindentation just above the respective inner body 102. The connection 124between the central support rod 120 and the inner body 102 providessupport and allows some heat transfer and mechanical support for aproper build. As shown in FIG. 2, an external tube 126 outboard of theswirl vanes 104 and outer rings 108 of the swirlers is built up from theexternal ring 114 to support the build from outside.

There is a respective ledge 128 protruding inward from the external tube126 for supporting the build of each of the outer rings 108. Thefrustoconical angle a of the swirl vanes described above with referenceto FIG. 1 is conducive to building up in additive manufacturing machinesfrom the ledges 128.

As shown in FIG. 3, several stacks 112 of swirlers 100 can be fit on asingle build plate 118. In this example, there are eight swirlers 100 ineach of nine stacks for a total of seventy-two swirlers 100 that can beproduced in a single additive manufacture build. Those skilled in theart will readily appreciate that any suitable number of swirlers in eachstack, and any suitable number of stacks can be included on a buildplate without departing from the scope of this disclosure.

After the build, e.g., the build on build plate 118 in FIG. 3, iscomplete, each stack 112 can be removed from the build plate 118. Theexternal tube 126, labeled in FIG. 2, can be machined away from thestack 112 using any suitable process such as turning down on a lathe,e.g., to the final braze diameter, to begin separating the swirlers 100from one another. The frangible features 122, 124 (labeled in FIG. 4)can then be broken to finish separating the swirlers 100 in the stack112 from one another. Breaking the frangible features 122, 124 caninclude twisting the swirlers relative to one another about the swirlaxis A. Any remnant features of the central support rod 120 can bemachined away from the swirler 100 using conventional techniques. Havingthe support structure 132 (labeled in FIG. 4) between the frangiblefeature 122 and the inner body 102 protects the inner body 102, e.g.,from being damaged during the additive manufacturing process. It is alsocontemplated that in addition to or in lieu of using the frangiblefeatures 122, 124, the swirlers 100 can be separated from one another bymachining away the central support rod 120, e.g., by drilling it downthe swirl axis A or using electrical discharge machining (EDM),resulting in swirlers 100 with a central aperture 130 through the innerbody 102 thereof. This central aperture 130 can be kept as a coolingbore, or can be plugged, e.g. by welding or brazing.

Systems and methods as disclosed herein provide swirlers that caneconomically be produced using additive manufacturing, while providingdesign flexibility needed for intricate features such as required inmodern engines, e.g. for stringent emissions requirements. Relative tothe number of swirlers that can be produced as disclosed herein, thereis little support clean up required after a build. The conicalgeometries disclosed herein provide for nearly self-supporting buildstructures and allow nesting within one another for compact andefficient manufacturing. The methods and systems of the presentdisclosure, as described above and shown in the drawings, provide forswirlers with superior properties including ease of manufacture. Whilethe apparatus and methods of the subject disclosure have been shown anddescribed with reference to preferred embodiments, those skilled in theart will readily appreciate that changes and/or modifications may bemade thereto without departing from the scope of the subject disclosure.

What is claimed is:
 1. A swirler comprising: an inner body defining a swirl axis; and a plurality of swirl vanes extending outward from the inner body, wherein the swirl vanes define respective swirl slots therebetween for imparting swirl on a fluid passing through the swirl slots.
 2. The swirler as recited in claim 1, wherein the inner body follows a first cone angle that diverges in a downstream direction along the swirl axis, wherein the swirl vanes define a frustoconical volume that follows a second cone angle that converges in the downstream direction.
 3. The swirler as recited in claim 1, wherein the swirl slots and swirl vanes are oriented tangential to the swirl axis.
 4. The swirler as recited in claim 1, further comprising an outer ring connected to the swirl vanes and providing an outward boundary to the swirl slots.
 5. The swirler as recited in claim 1, wherein the inner body has a constant wall thickness.
 6. The swirler as recited in claim 1, wherein the inner body defines a plurality of cooling holes therethrough inboard of the swirl slots. 